1. Field of the Invention
The invention relates to a drill rod pulling attachment for use with a rock or earth drilling machine, in particular a diamond drilling machine.
2. Prior Art
In a normal drilling operation, it is desirable to be able to pull the drill rods from the drill hole for bit change, core recovery, etc., and to replace them in the hole again in as little time as possible. A drilling machine has a feed mechanism normally used for feeding the drill rods in a forward direction whilst actually drilling and, with the rotary drive thereof inactive and feed direction reversed, the feed mechanism can also be used for withdrawing the drill rods from the hole, and in the forward feed direction for re-inserting the rods into the hole. When the feed mechanism that is usually used for drilling is used for the rod withdrawing and re-insertion operations, it is usually relatively slow as the feed mechanism for drilling is necessarily limited in its rate of feed and also the relatively short stroke of the feed mechanism. To reduce the time required for the above withdrawing and re-insertion operations it would be desirable to move the rods in an essentially continuous motion limited only by the available length of tail room or clear space in which the rod can move axially, and not by the relatively short stroke of the feed mechanism as is the common situation.
Essentially continuous rod pulling devices are known in which two wheels or rollers grip a drill rod, at least one of the wheels being powered for moving the rod axially. These pulling devices usually require a separate motor for powering at least one of the wheels, and this increases the complexity and overall size of the drilling machine and can restrict its convenience of operation particularly when operating underground. Two main types of drilling machines are in common use and the present invention to be described could be adapted to operate with some examples of either type. The first type is a top drive drilling machine which is relatively simple and rotates the drill rods by means of a rotating male portion which engages a complementary female portion at a rear end of the drill rod. The second type is a chuck drive machine in which a manual or remotely operated chuck grips the drill rods and is mounted on a powered hollow spindle, the drill rods passing through the spindle. In the specification and claims either structure for rotating the drill rod is referred to as rod rotating means, and the terms rod "puller," "pulling" or like terms refers to axial displacement of the drill rod in either direction.